问题 单项选择题 A1型题

关于妊娠期母体的变化,以下哪项正确()。

A.血浆白蛋白增加

B.每分钟肺通气量减少

C.肾小球滤过率减少

D.心脏移位、搏出量减少

E.凝血因子增加,纤溶活性降低

答案

参考答案:E

解析:妊娠期由于血液稀释,血浆白蛋白减少。妊娠期母体耗氧量增加,虽然膈肌升高,但胸廓横径增加,胸廓活动相应增加,每分钟肺通气量增加约40%。妊娠期母体血流量增加,耗氧量增加,心搏量增加20%~30%。肾轻度增大,肾盂及输尿管轻度扩张,肾血流量及肾小球滤过率均增加。妊娠期母体血液中凝血因子增加,纤溶活性降低,使孕妇血液处于高凝状态,是一种自然保护机制,以预防产后出血。

问答题
单项选择题

Nuclear power’s danger to health, safety, and even life itself can be summed up in one word: radiation.

Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can’t be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can’t detect them, sense them, without a radio receiver. Similarly, we can’t sense radio activity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.

At very high levels, radiation can kill an animal or human being outright by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no level of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be significant. This is the case when only a few cells are hit. And if they are killed outright, your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.

This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can he irradiated and feel fine, then die of cancer five, ten, or twenty years later as a result. Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents.

Radiation can hurt us. We must know the truth.

According to the passage, the danger of nuclear power lies in()

A. nuclear mystery

B. radiation detection

C. radiation level

D. nuclear radiation